Sydney siege inquest: could ASIO have done more?

AUSTRALIA'S national security hotline received 18 calls and emails about Man Haron Monis's Facebook page less than a week before the Sydney siege, an inquest has heard.

The inquest into the siege has begun considering what Australia's intelligence agencies knew about Monis and whether they should have intervened before he took Lindt Cafe customers and staff hostage on December 15 last year.

State coroner Michael Barnes told the inquest he would be questioning whether the Australian Security and Intelligence Organisation (ASIO) should have taken a "more active or interventionist" approach after receiving multiple warnings about Monis.

Questions provided by the families of victims Katrina Dawson and Tori Johnson, who were killed during the siege, will also be addressed during the forthcoming hearings, which will take place behind closed doors.

"All the world now knows that Monis was a dangerous deviant," Mr Barnes said.